Source : Webster's Revised Unabridged Dictionary (1913)

Additive \Ad"di*tive\, a. [L. additivus.] (Math.)
   Proper to be added; positive; -- opposed to {subtractive}.

Source : WordNet®

additive
     adj 1: characterized or produced by addition; "an additive process"
            [ant: {subtractive}]
     2: designating or involving an equation whose terms are of the
        first degree [syn: {linear}] [ant: {nonlinear}]

additive
     n : something added to enhance food or gasoline or paint or
         medicine

Source : Free On-Line Dictionary of Computing

additive
     
         A function f : X -> Y is additive if
     
         for all Z <= X
         f (lub Z)  =  lub { f z : z in Z }
     
        (f "preserves {lub}s").  All additive functions defined over
        {cpo}s are {continuous}.
     
        ("<=" is written in {LaTeX} as {\subseteq}, "lub" as \sqcup ).
     
        (1995-02-03)